Renoprotective Effect Of Caloric Restriction On Renal Lesions Of Insulin Resistance And Its Possible Mechanism

ObjectiveTo investigate the Renoprotective effect of caloric restriction on insulin resistance induced renal lesions in rats and initially explore its possible mechanism.Methods24 healthy male Wistar rats were randomly divided into 2 groups: normal control group(NC, n=8) received standard laboratory chow diet and high-fat feeding group(HFM, n=16) were fed with high-fat diet.Eight weeks later, the rats in Group HFM were further randomly divided into 2 subgroups: insulin resistance model group(IR, n = 8) and normal diet feeding with 50% calorie restriction group(CR, n=8).The rats were sacrificed after 4 weeks calorie restriction.At the end of a 12-week period, fasting plasma glucose, fasting insulin, serum lipid, visceral fat coefficient, urinary microalbumin excretion, contents of carbonyl protein and malondialdehyde(MDA), relative levels of vascular endothelial growth factor(VEGF) mRNA in renal cortex were detected.Meanwhile, the morphological alteration of kidney was analyzed by image analysis system.ResultsCompared with group NC, there were dilation of glomerular saccule(p<0.05), proliferation of extracellular matrix(p<0.05) and increase of urinary microalbumin excretion(p<0.05) in group IR.These nephropathies were associated with the upregulation of VEGF-mRNA expression and increase in contents of carbonyl protein and MDA(p<0.05).Caloric restriction can decrease the expression of VEGF-mRNA and the contents of carbonyl protein and MDA(p<0.05,vs group IR).It also reversed metabolic disorder and renal lesions induced by insulin resistance.ConclusionCaloric restriction can reverse the progression of insulin resistance induced renal lesions.These renoprective effects may be related to the depression of oxidative stress and consequently decreased level of VEGF.